At 13 months, salt-tolerant poplars planted at Oremet Titanium, Inc., in Albany, Ore., are already 12 feet tall.

Thirsty Hybrid Poplars Recycle Irrigation Water

Hybrid poplars may help the environment by drinking used irrigation water laden with salt, boron and selenium. Scientists say the fast-growing trees may also provide a new source of income for farmers who grow irrigated crops like tomatoes, melons, cotton and alfalfa in salty soils.

Today, some growers drain leftover irrigation water to evaporation ponds. That helps prevent minerals in the drainage water from flowing into rivers, streams and the underground water supply, called groundwater. In the future, with the help of the water- loving poplars, growers may need fewer--and smaller--evaporation ponds. This would reduce maintenance, including the costs of keeping wildlife from ponds where high levels of minerals accumulate.

The idea of using hybrid poplars to recycle water isn't new. But an Agricultural Research Service study of eight different kinds of candidate hybrid poplars was among the first to examine the trees' ability to withstand chloride salt, boron and selenium in the amounts sometimes present in irrigation drainage.

No experimental poplar was as salt-tolerant as eucalyptus, an extremely fast-growing species sometimes chosen for water re-use. The market for hybrid poplar is stronger, however. It can be made into everything from toothpicks and high-quality veneer to paper.

Michael C. Shannon of the U.S. Salinity Laboratory at Riverside, Calif., and Gary S. Banuelos of the ARS Water Managment Research Laboratory at Fresno, led the study. Ecolotree, Inc., of Iowa City, Iowa, provided 6-inch cuttings, which averaged about six feet tall by the end of the five-month experiment. Findings should apply to parts of California, Arizona, New Mexico, Texas and Colorado. Hybrid poplars might also help re-use saline effluent from factories around the nation.

An article in the June issue of ARS' monthly magazine, Agricultural Research, tells more. View it on the World Wide Web at:

http://www.ars.usda.gov/is/AR/archive/jun98/salt0698.htm.

Scientific contacts: Michael C. Shannon, ARS U.S. Salinity Laboratory, Riverside, CA 92507, phone (909) 369-4815, fax (909) 342-4960, mshannon@ussl.ars.usda.gov; and Gary S. Banuelos, ARS Water Management Research Unit, Fresno, CA 93727, phone (209) 453-3115, fax (209) 453-3122, sdowney@asrr.arsusda.gov.